1. Field of the Invention
The present invention generally relates to semiconductor processing technologies and, more particularly, to a system and process that removes a conductive layer from the edge and/or bevel of a work piece.
2. Description of the Related Art
In the semiconductor industry, various processes can be used to deposit and etch conductive materials on the wafers. Deposition techniques include processes such as electrochemical deposition (ECD) and electro chemical mechanical deposition (ECMD). In both processes, a conductor is deposited on a semiconductor wafer or a work piece by having electrical current carried through an electrolyte that comes into contact with the surface of the wafer (cathode). A detailed description of the ECMD method and apparatus can be found in U.S. Pat. No. 6,176,992 to Talieh, entitled ‘Method and Apparatus For Electro Chemical Mechanical Deposition’, commonly owned by the assignee of the present invention.
Regardless of which process is used, the work piece is next transferred to a cleaning and drying station after the deposition step. During the cleaning steps, various residues generated by the deposition process are rinsed off the wafer, and subsequently the wafer is dried by spinning and if necessary blowing nitrogen on its surface. In one design, the ECD or ECMD chamber and the rinse chamber can be stacked vertically in a vertical process chambers arrangement. In this arrangement, the plating process can be performed in a lower chamber, and the cleaning and drying can be carried out in an upper chamber after isolating the upper chamber from the lower chamber. One such vertical chamber is disclosed in U.S. Pat. No. 6,352,623, entitled ‘Vertically Configured Chamber Used for Multiple Processes’, filed Dec. 17, 1999, commonly owned by the assignee of the present invention.
Conventionally, after the plating process is performed to deposit the conductive material, the work piece may be polished mechanically and chemically, e.g., chemical mechanical polishing (CMP), so as to remove overburden conductive material from the front face of the work piece. As is known, the material removal can also be carried out using chemical etching or electrochemical etching. In electrochemical etching, the wafer is made anodic (positive) with respect to an electrode after completing an ECD or ECMD process.
Copper is a preferred conductive material that can be deposited by ECD and ECMD processes. Therefore it will be used as an example. As a result of electroplating process, copper may be deposited on the edges and sides, i.e., bevel, of the wafer where no ICs or circuits are located. Such remaining copper, which is often referred to as the edge copper, may migrate to neighboring active regions from the sides and edges of the wafer. Further, copper from a wafer edge may contaminate the wafer transport system, and so be passed on to contaminate other wafers. For this reason, it is important to remove the copper from the edges and the bevel of the wafer following each copper plating process step.
To this end, there is a need for removing edge copper in copper plating processes in an efficient and effective manner with high throughput.